feat: implement prover backend

[0xpanoramix]

Description

This PR adds the Rust prover backend.

Changes include

• Bugfix (non-breaking change that solves an issue).
• Hotfix (change that solves an urgent issue, and requires immediate attention).
• New feature (non-breaking change that adds functionality).
• Breaking change (change that is not backwards-compatible and/or changes current functionality).
• Documentation update (change added to any kind of documentation).

Breaking changes

Please complete this section if any breaking changes have been made, otherwise delete it.

Checklist

• I have assigned this PR to myself.
• I have added at least 1 reviewer.
• I have added the relevant labels.
• I have updated the official documentation.
• I have added sufficient documentation in code.

Testing

• I have tested this code with the official test suite.
• I have tested this code manually.

Manual tests

Please complete this section if you ran manual tests for this functionality, otherwise delete it.

Documentation update

Please link the documentation update PR in this section if it's present, otherwise delete it.

Additional comments

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